1. Field of the Invention
The present invention relates to data storage media for storing digital data, and particularly, to data storage media having certification data.
2. Description of the Related Art
Various types of information in characters, images, video, and audio are presently handled as digital data. To record digital data and programs, a variety of storage media such as tapes, floppy disks, hard disks, and magneto-optical disks are used.
The floppy disks are one of popular media. When data are written or read, the floppy disks need to be rotated. Therefore, the disk-drives must have a motor and a rotating mechanism. Due to this, the floppy disks are improper for electronic devices that must be small and light.
Portable electronic devices need external data storage media that are small and light and ensure compatibility among various types of electronic devices.
Data storage media that meet these requirements are those having nonvolatile semiconductor memories which are electrically rewritable. For example, card-type data storage media incorporating nonvolatile semiconductor memories are suitable for the portable electronic devices. Many techniques have been developed to record contents such as still images, voice, and music in the card-type data storage media.
Unlike analog data, digital data never deteriorates even if it is repeatedly copied among data storage media. It is required, therefore, to provide a technique of preventing the illegal copying of digital contents.
In particular, electronic commerce and electronic banking must prevent the illegal alteration and copying of data, in particular, personal identification data stored in data storage media.